If you aren't dining alone...don't order two dinners. You can get one entree and an appetizer and still get ample food.
Also try and make a second meal out of leftovers.
You might try just ordering a side item for meal.
Try to get lunch special when available.
Also look out for special days such as family days that allow kids to eat free.
Drink water when you're eating out. Sodas and alcoholic beverages are much cheaper at a grocery store.
Also skip dessert...picking up a carton of ice cream on your way home will save you a bunch.